Automatic follower control for web tensioning



Feb. l, 1966 H. c. RATHMANN 3,232,551

AUTOMATIC FOLLOWER ONTROL FOR WEB TENSIONING Filed Nov. 19. 1962 /F/zea stia INVEN TOR. RA

HENRY C. Tl-IMAXVC BY 7 United States Patent 3,232,551 AUTMATIC FOLLOWER CONTRL FOR WEB TENSIQNING Henry C. Rathmarm, Vestal, NX., assigner to General Aniline & Film Corporation, New York, N.Y., a corporation of Delaware Filed Nov. 19, 1962, Ser. No. 238,433 3 Claims. (Cl. 242-7545) This invention relates to an apparatus for controlling the tension in a web material passing from a supply roll to a take-up roll, and relates more particularly to web processing machinery where predetermined torque variations of an unwind spindle are requried. Specifically, the instant invention is directed to a follower control for sensing the changing diameter of an unwinding roll of web material and mechanically transmitting this information to a voitage regulating means which varies the input voltage to a magnetic or hysteresis brake mounted on the unwind spindle, thereby controlling the tension on the web as it is withdrawn from the roll.

In web processing machinery, there are conventionally employed rolls of web material, known as the supply or pay-out rolls, which are mounted on rotatable spindles and function to provide a supply of web material to be processed. The web material is withdrawn from the rolls by a driven take-up or rewind roll. It is essential in such processing machinery to rewind the web material on the take-up roll under a predetermined tension. This is ordinarily accomplished by providing braking means on the unwind spindle. However, as the web material is withdrawn from the supply roll, the diameter of this roll is gradually decreased; whereas the diameter of the spindle remains constant. Therefore, the winding tension tends to decrease as the processing progresses. Various compensating means have been provided in the past for maintaining the tension at a desired level regardless of the changing diameter of the roll of web material being unwound. Floating, or dancer, rolls have heretofore been inserted in the path of the web material, these rolls being so mounted that variations in the web tension causes displacement of the dancer-roll axis. Dancer-rolls have been found to be unsatisfactory in many web processing machines because they tend to he sluggish and do not respond to the fluctuations in the web tension as rapidly as might be desired. It has also been common practice in the past to provide a follower means which is maintained in contact with the periphery of the unwinding roll of web material and which functions, as the diameter of the roll decreases, to modify the braking force or frictional drag on the unwind spindle and thereby maintain the desired tension on the web material as it passes to the take-up roll. Prior art follower means have been unable to insure strict uniformity in the winding tension because they have either relied on the weight of the follower arm to drive the tension-varying means, or they have not provided for a positive linkage between the movement of the follower arm and the means for varying the web tension. These deiiciencies have caused the compensating means to be both slow in responding to the changing roll diameter, and unreliable.

in most instances, a constant web tension is desirable. However, where a narrow Web is wound to a large di- ,ameter under constant tension, the wound roll is sub- 3,232,551 `Eatented Feb. l, i956 ICC ject to telescoping. It would be advantageous in such cases, to taper the tension on the web material as it is rewound, i.e., to wind the inner portion of the take-up roll more tightly than the outer portion. This can be accomplished by winding the inner portion under greater tension. Prior art tensioning devices have not provided satisfactory means for effectively controlling this tapered tension.

An important object of this invention is to provide web tensioning means which are free from the foregoing and other disadvantages.

Another object of the instant invention is the provision of apparatus of the type describe-d having substantially instantaneous compensatory action.

A further object of this invention is to provide means which maintain the web tension constant over the full change in diameter of the supply roll.

Another object of the invention is the provi-sion of means for controllably decreasing the tension on the web material as the diameter of the supply roll decreases in order to wind the inner portion of the web material on the taire-up roll more tightly than the outer portion.

Another object of this invention is to provide web tensioning means which are easily convertible from means for providing constant tension on the web material to means for providing tapered tension.

A further object of the instant invention is to provide a magnetic or hysteresis type brake on the unwind spindle, the input voltage to which is varied through a system of mechanical and electrical linkages by the movement of a `roll follower means maintained in contact with the pe- .that a new roll of web material may be fitted on the unwind spindlewithout hindrance.

t is further contemplated to provide an automatic voltage regulating means for varying the input voltage to the brake in response to the changing roll diameter, in combination with manually operated voltage regulating means for setting a desired starting web tension.

Other objects and advantages of this invention, with certain details of construction and combination of parts, will appear from the following detailed description 'and will be particularly pointed out in the appended claims.

The accompanying drawing shows a preferred embodiment of the invention with the shell partly broken away to show the hidden parts.

In the drawing, reference numeral 1 designates the unwind spindle of a web processing machine. The spindle 1 supports a roll of web material 2 for rotation therewith. The outer periphery of a full roll of web material is shown by the dot-dash lines 2a. Web material is withdrawn from this supply roll 2 by a rewind or take-up roll (not shown). A magnetic or hysteresis type brake is mounted on the unwind spindle 1 for applying a variable frictional drag to the same. The brake receives power from a remote source of voltage. The amount of frictional drag on the unwind spindle i determines the tension on web material withdrawn from the supply roll 2.

The reference numeral 3 designates a face-plate of a web processing machine. Mounted on this face-plate 3 is a voltage regulating means, such as a rheostat, shown diagrammatically at 4. This rheostat 4 may be a numb'er l() Powerstat or any other similar device. The

B v rheostat 4 is operatively connected to the magnetic brake in the conventional manner. It functions to vary the input voltage to the brake in response to an angular movement of the well-known brush contact on the rheostat.

A roll follower 5 is normally maintained in contact with the periphery 2a of the roll of web material 2 by a roll follower arm 6. The roll follower arm 6 is fixed to a shaft 7 rotatably supported in the face-plate or Ymounting plate 3 at the end of the roll `follower arm e, remote from the roll follower 5. The roll follower arm 6 is therefore pivotally supported in the mounting plate 3. A plate-type cam 8 is mounted on the shaft 7 and turned thereby in the directions indicated by the twoheaded arrow on its surface. The plate-type cam S is mounted on the shaft 7 by a plurality of mounting screws (not shown). The cam has slotted mounting holes so that adjustment is possible after assembly. The camming surface 3a on the plate-type cam S has a high portion 8b and a low portion 8c. In accordance with a further feature of this invention, the camming surface 8a may also have a notch as at 8d, the purpose of which will be explained hereinafter. Reference numeral 9 designates a cam follower which is attached to one end of a cam follower arm 10. The cam follower arm 1l) is fixed to a second shaft 11 at a point approximately midway between the two ends of the arm. The second shaft 11 is rotatably supported in the mounting plate 3. A spring 12 is attached to the end of the cam follower arm remote from the cam follower 9, and acts to pivot the cam follower arm iti counter-clockwise, as seen in the drawing, about its pivot point on the second shaft 11. This pivoting force normally maintains the cam follower 9 in contact with the camming surface 8a of the plate-type cam 3. The spring 12 is adjusted by adjusting screw 13 to vary the pivoting force on the cam follower arm 10, A gear 14 is fixed to, and turned by, the second shaft 1i. A series of amplifying gears are driven by the gear 14 and are operatively connected to the brush contact (not shown) on the rheostat 4. Three such gears are shownat 15, 16 and 17.

The foregoing briefly describes the mechanical features of the web tensioning means. Its preferred mode of voperation is as follows:

A full roll of web material 2 is loaded on the unwind spindle 1. This will be referred to hereinafter as the supply roll. The web processing machinery is actuated, and a take-up roll (not shown) functions to continuously withdraw web material from the supply roll 2. The roll follower S is maintained in contact with the periphery 2a of the supply roll 2. The roll follower arm 6 pivots about its fixed end as the diameter of the supply roll 2 decreases and the roll follower 5 approaches the unwind spindle 1. As the roll follower arm 6 pivots in this manner, it turns the shaft 7 in a counter-clockwise direction. The movement of the shaft 7 rotates the platetype cam 8, fixed thereto, in the same direction. The cam follower 9 is maintained in contact with the camming surface 8a of the plate-type cam S by the pivoting action of the spring 12 on the cam follower arm 10. As the plate-type cam 8 turns counterclockwise, the cam follower 9 follows the contour of the camming surface 8a from the high portion 8b, which it contacts when the supply roll 2 is full, to the low portion 8c, which it contacts Y when the supply roll 2 is empty. The cam follower arm 10 pivots about the second shaft 11 as the cam follower 9 `moves upward, as seenV in the drawing, in response to the changing camming surface 8a. The short, angular movement of the cam follower arm 1d is amplified by the gear train 1li-17, which is driven in response to the turning of the second shaft l1 by the cam follower arm 10. The gear train 14-.17 drives the brush contact on the rheostat 4, thereby varying the input voltage to the magnetic brake and the frictional drag on lthe unwind spindle 1. The frictional drag on the unwind'spindle 1 determines the tension on the unwinding web.

The camming surface 8a on the plate-type cam 8 can be made to conform tothe characteristics of the particular unwind brake employed. The contour of the camming surface 8a may be varied depending on whether it is desired to maintain the tension on the web constant over the full change in diameter of the supply roll 2, or tapered, as the diameter of the supply roll 2 decreases. One plate-type cam S can be removed from the shaft 7 and replaced by another cam having a diiferent camming surface contour, by simply removing the cam mounting screws.

The notch 8d in the camining surface da of the platetype carn 8, referred to earlier, is a further feature of the instant invention which adds `to its versatility. When the roll follower arrn; Vis raised in order to load a new roll of web material 2 on the unwind spindle 1, the cam follower 9 is forced into the notch Sd by the pivoting action of the spring l2 on the cam follower arm 1li. The cam follower 9 then acts as a detent to hold the roll follower arm 6 in an up position while the new roll of web material is loaded on the unwind spindle 1. It will not release the roll follower arm 6 until the arm is manually rought down so that the roll follower SV makes contact with the periphery 2a of the roll of web material 2. Manual pressure on the roll follower arm 6 will overcome the force of the spring 12, which normally actsrto maintain the cam follower 9 in the notch 8d. l

To make the web tensioning means of the4 instant invention even more versatile, Va manually operated rheostat can be used in Iconjunction with the automaticallyoperated rheostat 4. This allows the machine operator to set a desired starting web tension for a machine which processes more than one type of web material.

It is emphasized again that the rheostat 4 in the instant invention is not driven by the weight of the roll follower arm 6, but is self-driven. That is, the brush contact on the rheostat 4 is actually driven by the spring loaded caml follower arm 1li through the Vsystem of arnplifying gears fdr-17 in response to a change in the diameter of the unwinding supply roll 2, as sensed by the roll follower arm 6.

The present invention may be embodied in other specific forms without departing from the spirit of the invention.

What is claimed is:

1. Apparatus for the tensioning of web material cornprising, in combination, a rotatable spindle for supporting a roll of web material, a magnetic brake mounted on said spindle, said brake receiving power-from a voltage source, a roll follower normally maintained in contact with the periphery of said roll of web material, a mounting plate,

`a shaft lrotatably supported in said mounting plate, a roll follower arm attached at one end to said roll follower and fixed at the other end to said shaft, a plate-type cam mounted on said shaft, a camming surface on said platetype cam, a cam follower, a cam follower arm fixed at one end to said cam follower and pivotallyV mounted on said mounting plate between the extremities of said cam follower arm, and adjustable tensioning means attached to the .end of said cam follower arm remote from said cam fol- .with said cam follower when said roll of web material is at its maximum diameter, and* said low portion being in contact with said cam follower when said roll of web material is at its minimum diameter, a notch in the camming surface of said plate-type cam, said notch being so placed that when said cam follower is Within said notch the follower arm is supported in a position further from 5 said spindle than the maximum diameter of a full roll of web material.

3. Apparatus in accordance with claim It, comprising further in combination with the automatically operated rheostat, a manually operated rheostat said manually 0perated rheostat being adapted for setting a desired starting web tension on the apparatus for the tensioning of web material.

References Cited by the Examiner UNITED STATES PATENTS 1,652,299 12/ 1927 Carpenter 242-7545 1,822,495 9/ 1931 Laycock 242-75 .45 2,750,921 6/ 1956 Purdy 242-7545 X FOREIGN PATENTS 425,617 3/ 1935 Great Britain. 842,328 6/ 1952 Germany. 1,140,087 2/ 1957 France.

MERVIN STEIN, Primary Examiner.

DONALD W. PARKER, Examiner. 

1. APPARATUS FOR THE TENSIONING OF WEB MATERIAL COMPRISING, IN COMBINATION, A ROTATABLE SPINDLE FOR SUPPORTING A ROLL OF WEB MATERIAL, A MAGNETIC BRAKE MOUNTED ON SAID SPINDLE, SAID BRAKE RECEIVING POWER FROM A VOLTAGE SOURCE, A ROLL FOLLOWER NORMALLY MAINTAINED IN CONTACT WITH THE PERIPHERY OF SAID ROLL OF WEB MATERIAL, A MOUNTING PLATE, A SHAFT ROTATABLY SUPPORTED IN SAID MOUNTING PLATE, A ROLL FOLLOWER ARM ATTACHED AT ONE END TO SAID ROLL FOLLOWER AND FIXED AT THE OTHER END TO SAID SHAFT, A PLATE-TYPE CAM MOUNTED ON SAID SHAFT, A CAMMING SURFACE ON SAID PLATETYPE CAM, A CAM FOLLOWER, A CAM FOLLOWER ARM FIXED AT ONE END TO SAID CAM FOLLOWER AND PIVOTALLY MOUNTED ON SAID 